Bodily injuries and ailments are commonly treated by applying a non-ambient temperature material to the affected region of the body. For example, a low temperature material, typically applied in the form of cold water, ice or a cold pack, may advantageously inhibit swelling in the region of the injury. A high temperature material, typically applied in the form of hot water, a hot pack or an active heating element, may advantageously reduce pain and promote healing. A number of splint devices are known in the art for applying non-ambient temperature materials to injured or otherwise ailing regions of the body as evidenced by U.S. Pat. No. 3,548,819 to Davis et al; U.S. Pat. No. 3,901,225 to Sconce; and U.S. Pat. No. 4,706,658 to Cronin. One disadvantage of such devices is that the low temperature materials become warmer as they remain in contact with the body during treatment and the body transfers heat to the low temperature materials. Conversely, high temperature materials become cooler as they transfer heat to the body. This disadvantage can be remedied by periodically replacing the non-ambient temperature materials. However, constant replenishment of these materials is cumbersome and inconvenient, and results in periodic treatment temperature fluctuations.
In response to this problem, a number of systems have been developed for continuously circulating a cooling fluid from a low temperature reservoir to a desired body location. Such systems are typified by U.S. Pat. No. 2,726,658 to Chessey; U.S. Pat. No. 3,683,902 to Artemenko et al; and U.S. Pat. No. 4,962,761 to Golden. These fluid circulation systems in general are relatively complex, rendering them costly to manufacture and maintain, as well as difficult to operate. Accordingly, the systems are not practical for widespread use.
U.S. Pat. No. 5,241,951 to Mason et al. incorporated herein by reference discloses a therapeutic treatment system which rectifies the shortcomings of the above-referenced fluid circulation systems. The therapeutic treatment system of U.S. Pat. No. 5,241,951 is relatively simple, rendering it less costly to manufacture and maintain and enabling greater ease of operation than the prior systems. The system of U.S. Pat. No. 5,241,951 includes a fluid reservoir, a submersible single-speed pump, a pliant heat transfer pad having pad inlet and outlet ports and an internal pad flowpath, system inlet and outlet lines connecting the internal pad flowpath to the pump via the pad inlet and outlet ports, and a user adjustable in-line flow control valve.
The therapeutic treatment system of U.S. Pat. No. 5,241,951 is operated by filling the fluid reservoir with a non-ambient temperature heat transfer fluid and submersing the pump in the heat transfer fluid. The heat transfer pad is positioned at a desired treatment region of the body, conformed to the contours of the treatment region, and mounted thereon. The pump is activated to deliver fresh heat transfer fluid from the fluid reservoir to the internal pad flowpath via the system inlet line and pad inlet port and to return spent heat transfer fluid from the internal pad flowpath to the fluid reservoir via the pad outlet port and system outlet line. The patient regulates the treatment temperature of the heat transfer pad by manually adjusting the flow control valve to control the flow rate of heat transfer fluid through the internal pad flowpath.
Specific examples of prior art heat transfer pads having utility in the therapeutic treatment system of U.S. Pat. No. 5,241,951 are disclosed in commonly-owned U.S. Pat. No. 5,417,720 to Mason et al. and U.S. Design Patents Des. 348,106 and Des. 345,609 to Mason et al., all of which are incorporated herein by reference. A prior art heat transfer pad of the type disclosed in the above-listed patents is shown and described with reference to FIGS. 1 and 2. The heat transfer pad is generally designated 100 and includes a first pad port 102, a second pad port 104, and a bladder 106.
The bladder 106 is a planar member comprising an inner sheet 108 and an outer sheet 110. The inner and outer sheets 108, 110 are each formed from a plastic film and are identically shaped to be laid one atop the other. The inner and outer sheets 108, 110 are peripherally bonded by conventional means such as welding to one another and to the first and second pad ports 102, 104 to define a peripheral seal 112. The inner and outer sheets 108, 110 are also periodically bonded together at a plurality of points interior to the peripheral seal 112 which are not contiguous with the peripheral seal 112 to define a plurality of flow diverters 114. The peripheral seal 112 and flow diverters 114 enclose and delineate a tortuous internal flowpath for a non-ambient temperature heat transfer fluid through the void space between the inner and outer sheets 108, 110 of the bladder 106.
The first and second pad ports 102, 104 are positioned side-by-side with the first pad port 102 being an inlet port and the second pad port 104 being an outlet port for the internal flowpath of the bladder 106. The first pad port 102 includes a first tubing segment 116 having a proximal end 118 and a distal end 120. The proximal end 118 extends between the peripheries of the inner and outer sheets 108, 110 of the bladder 106 which are permanently bonded to the outer wall of the proximal end 118, thereby maintaining the continuity of the peripheral seal 112 at the first pad port 102. The proximal end 118 is ribbed to strengthen the bond between the proximal end 118 and the inner and outer sheets 108, 110.
The second pad port 104 similarly includes a second tubing segment 122 having a proximal end 124 and a distal end 126. The proximal end 124 extends between the peripheries of the inner and outer sheets 108, 110 of the bladder 106 which are permanently bonded to the outer wall of the proximal end 124, thereby maintaining the continuity of the peripheral seal 112 at the second pad port 104. The proximal end 124 is ribbed to strengthen the bond between the proximal end 124 and the inner and outer sheets 108, 110. The proximal ends 118, 124 of the first and second tubing segments 116, 122 are open to the internal flowpath of the bladder 106, but are separated from direct fluid communication with one another by the flow diverters 114.
The distal ends 120, 126 of the first and second tubing segments 116, 122, respectively, extend away from the bladder 106 in the opposite direction as the proximal ends 118, 124. The distal ends 122, 126 have first and second port couplings 128, 130, respectively, positioned across them. The first and second port couplings 128, 130 are configured to cooperatively and releasably mate with first and second line couplings, respectively, included in the first and second system fluid circulation lines, respectively, which are not shown herein, but are shown and described in U.S. Pat. No. 5,241,951.
The heat transfer pad 100 is further provided with insulating means to diminish heat transfer between the heat transfer pad 100 and the surrounding environment. In particular, an insulating foam sheet 132 is bonded to the outside face of the outer sheet 110 and an insulating port sheath 134 (shown partially cut away) extends between the first and second port couplings 128, 130 and the bladder 106 and covers the first and second tubing segments 116, 122.
The heat transfer pad 100 generally provides effective therapeutic treatment to the body when used in conjunction with the therapeutic treatment system of U.S. Pat. No. 5,241,951. Nevertheless, it has been found in some cases that the first and second pad ports 102, 104 are prone to occlusion when the heat transfer pad 100 is mounted on the body of a patient in conformance with the contours of the treatment region. For example, with reference to FIGS. 3 and 4, the heat transfer pad 100 is shown mounted on the flexed knee 136 of a patient. The fluid reservoir 138 is positioned at an elevated location relative to the heat transfer pad 100, which requires the user to angle the first and second tubing segments 116, 122 relative to the bladder 106 to achieve fluid communication between the first and second pad ports 102, 104 and the fluid reservoir 138.
However, angling the first and second tubing segments 116, 122 flexes the bladder 106 near the openings of the respective proximal ends 118, 124 because the bladder 106 is substantially more flexible than the first and second tubing segments 116, 122 at the flexion point. When the first and second tubing segments 116, 122 are flexed at angles of about 90 degrees or more as shown, the bladder 106 becomes kinked or pinched near the openings of the respective proximal ends 118, 124, respectively, thereby occluding the first and second pad ports 102, 104. Thus, angling the first and second tubing segments 116, 122 relative to the bladder 106 impedes the flow of the heat transfer fluid through the internal pad flowpath and undesirably diminishes the effectiveness of the therapeutic treatment.
U.S. Pat. No. 5,662,695 to Mason et al. discloses a pad which is specifically constructed to resist occlusion due to pinching or kinking of the bladder in the region of the pad inlet and outlet ports. In particular, the peripheral region of the bladder adjacent to the pad inlet and outlet ports is constructed in a manner which renders the peripheral region more rigid than the remainder of the bladder. The rigidity is increased by affixing a patch to the surface of the bladder adjacent to the pad inlet and outlet ports which provides the patched area with a greater cross-sectional thickness than the remainder of the bladder.
The present invention recognizes the need for an alternate solution to the above-recited occlusion problem. Accordingly, it is generally an object of the present invention to provide a non-ambient temperature heat transfer pad having improved resistance to occlusion. More particularly, it is an object of the present invention to provide an improved non-ambient temperature heat transfer pad having pad inlet and outlet ports which are less prone to occlusion when the pad is mounted on the body of a patient during operation of a therapeutic treatment system. These objects and others are achieved in accordance with the invention described hereafter.